Logan Cox died Sunday morning at Carolinas Medical Center in Charlotte, North Carolina, according to officials. His grandmother, Teresa Clevinger, told 911 operators that her daughter had been watching the boy last Wednesday but dozed off while at the family's home in Buford, which is in South Carolina, near the North Carolina line.

"He had figured out how he could unlock the doors," Clevinger said in the recording, which was obtained by WSOC-TV. "He got outside, and we don't know how long he's been out there."

Logan suffered severe heat stroke after he climbed into a car and became trapped, according to the Lancaster County sheriff's office. Authorities have said they weren't sure how long the boy was in the car, but Clevinger told the operator that her daughter had slept for about 30 minutes.

The boy's mother, Amber Bender, is heard later in the recording telling the operator that her boyfriend, Logan's father, was trying to cool the boy down.

"They're putting water on him, making sure he's cooled off and all," Bender tells the operator, who warns that putting the boy directly in cold water could cause shock.

There was no phone number listed for the family's home, and authorities haven't said if anyone will be charged in the boy's death.